Agricultural combine harvesters are used in the harvesting of grains in order to harvest and to thresh plants cultivated in a field. The threshed crop is subsequently also processed by a separating device. The grain obtained in the threshing and separating process is cleaned in a cleaning device and deposited in a grain tank, from which it is finally transferred to a transport vehicle.
In order to unload the grain tank, use is customarily made of a screw conveyor which is pivotable about the vertical axis between a pivoted-out unloading position, in which it extends transversely with respect to the forward direction, and a transport position which is pivoted rearward. In order to keep the output end of the screw conveyor as high as possible over the base at a given height of the grain tank base (and therefore also to be able to move transport vehicles of relatively high construction under the output end of the screw conveyor), customary screw conveyors (see, e.g., EP 1 186 222 A1) include a first portion which extends approximately vertically upward and to which a second, horizontal portion is connected. The two portions are connected to each other by a transition housing which is angled by approximately 90° and in which the conveyor screws of the two portions are coupled to each other in terms of drive by drive elements (propeller shafts).
A certain spatial distance that is not passed over by actively driven conveyor elements arises in the transition housing between the first conveyor screw and the second conveyor screw. Furthermore, the flow of crop is deflected and, in addition, in many embodiments, the cross section is tapered from the first toward the second screw conveyor. In the event of certain crop conditions (e.g., in the event of relatively moist grain or small grain dimensions which cause a low ratio between volume and therefore mass and surface such as in the case of grass seeds, and which therefore cannot be readily thrown through the transition housing), these circumstances may lead to transfer problems and to clogging.
Conventional solutions to this problem (e.g., AT 365 401 B, GB 1 038 037 A and U.S. Pat. No. 4,093,087 A) provide conveyor elements in the form of blades, paddles, or the like which are fitted to a connecting shaft between the two conveyor screws. However, they do not lead in all cases to a satisfactory conveying behavior and prevent the connecting shaft together with its joints from being able to be covered. Accordingly, the conveyed grain also comes into contact with the lubricant of the joints and can be mechanically damaged by elements of the joints moving relative to one another.
Thus, there is a need for a combine harvester equipped with a screw conveyor that overcomes many of the problems in the art.